Quantities in Chemical Reactions

Transcription

1 Unit 3 Quantities in Chemical Reactions Table of Contents Unit 3 Quantities in Chemical Reactions at a Glance STSE, Skills, and Basic Concepts in Unit Differentiated Instruction Assessment Summative Assessment: Unit 3 Project scienceontario Links for Unit Chapter 5 Chapter 6 Chapter 7 The Mole: A Chemist s Counter Specific Expectations Ideas for Launching the Chapter Common Misconceptions Differentiated Instruction Activities and Investigations Quick Reference Activity Notes and Answers Investigation Notes and Answers Proportions in Chemical Compounds Specific Expectations Ideas for Launching the Chapter Common Misconceptions Differentiated Instruction Activities and Investigations Quick Reference Activity Notes and Answers Investigation Notes and Answers Chemical Reactions and Stoichiometry Specific Expectations Ideas for Launching the Chapter Common Misconceptions Differentiated Instruction Activities and Investigations Quick Reference Activity Notes and Answers Investigation Notes and Answers Curriculum Correlations are found at the end of the Introduction. Answers to all questions not found in activities and investigations are in the Answer Key at the back of this Teacher s Resource. Unit 3 Quantities in Chemical Reactions MHR TR 3-1

2 Unit 3 Quantities in Chemical Reactions at a Glance Relationships in chemical reactions can be described quantitatively. The efficiency of chemical reactions can be determined and optimized by applying an understanding of quantitative relationships in such reactions. STSE Basic Concepts Investigation Skills Relating Science to Technology, Society, and the Environment Case Study: Prescription for Safety, p. 248 Chemistry Connections: Mass Spectrometer, p. 281 Case Study: Industrial-sized Safety, p. 328 Inquiry Investigation 6-B Chemical Analysis Simulation, p. 284 Unit 3 Project: Modelling Copper Recovery in the Electronics Industry, p. 336 STSE 5.1 The Mole and the Avogadro Constant 5.2 Mass and the Mole 6.1 Chemical Proportions and Percent Composition 6.2 Empirical and Molecular Formulas 7.1 What Is Stoichiometry? 7.2 Limiting and Excess Reactants 7.3 Reaction Yields Chapter 5 Launch: Quantitative Accuracy Matters, p. 223 Chapter 6 Launch: Comparing Compounds, p. 257 Chapter 7 Launch: Comparing Mole Relationships, p. 295 Activity 7.3 Stoichiometric Applications, p. 312 Activity 7.4 Increasing Percentage Yield, p. 320 Activities 3-2 MHR TR Unit 3 Quantities in Chemical Reactions

3 Developing Skills of Investigation and Communication Understanding Basic Concepts 5.1: One Big Pile of Pennies, p : Mass Percent of Oxygen, p : Exploring Formulas Using Models, p. 276 Quirks and Quarks: Bubbling Methane in the Beaufort Sea, p. 280 Chapter 7 Launch: Comparing Mole Relationships, p : Chalk It Up to Molar Relationships, p : Identify the Limiting Item, p : Stoichiometric Applications, p : Increasing Percentage Yield, p. 320 Investigation Skills 5-A: Exploring Conversions between Mass and Particles, p B: Using the Mole for Measuring and Counting Particles, p A: Determining the Percentage Composition of Magnesium Oxide, p B: Chemical Analysis Simulation, p C: Determining the Chemical Formula for a Hydrate, p A: Limiting and Excess Reactants, p B: Finding the Percentage Yield of a Single Displacement Reaction, p C: Finding the Percentage Yield of a Double Displacement Reaction, p The Mole and the Avogadro Constant 5.2 Mass and the Mole Basic Concepts What Is Stoichiometry? 7.2 Limiting and Excess Reactants 7.3 Reaction Yields 6.1 Chemical Proportions and Percent Composition 6.2 Empirical and Molecular Formulas 6 Unit 3 Quantities in Chemical Reactions MHR TR 3-3

4 STSE, Skills, and Basic Concepts in Unit 3 Relating Science to Technology, Society, and the Environment Chapter 5 The Mole: A Chemist s Counter Throughout the chapter, students analyze processes in the home (uses of baking soda, road salt, and magnesium hydroxide) and in industry (hydrazine in an air bag, sulfur dioxide from a power plant exhaust stack, and phosphoryl chloride in flame retardant) that involve the use of chemical quantities and calculations (Expectation D1.1). Chapter 6 Proportions in Chemical Compounds Students investigate the chemical properties of ASA and salicylic acid (Chapter 6 Launch). Nitrogen dioxide, a component in smog, and dinitrogen tetroxide, a rocket propellant, are used to illustrate how compounds with the same empirical formula can have different properties (Section 6.2). Information on applications of percentage composition in metal refining (Section 6.1) sets the stage for a class discussion on mining and the potential impact on the environment if quantitative accuracy is not observed (D1.2). Chapter 7 Chemical Reactions and Stoichiometry The process of sodium bicarbonate decomposition introduces the concept of reaction yield (Chapter 7 Launch). Throughout the chapter, sample problems analyze processes in the home and workplace that involve the use of chemical quantities and calculations (Expectation D1.1). Section 7.1 What Is Stoichiometry? uses environmental examples to emphasize the importance of quantitative accuracy (Expectation D1.2). Students research products that involve the use of stoichiometry and limiting and excess reactants (Activity 7.3) and explore how increasing percentage yield can help manufacturers to control costs and avoid costly clean-up of toxic waste (Activity 7.4). STSE Features Case Study: Prescription for Safety (student textbook page 248) outlines medication errors resulting from an incorrect use of units and Case Study: Industrial-sized Safety (student textbook p. 328) delineates differences between laboratory work and industrial processes with respect to both safety and scale (Expectation D1.2). Chemistry Connections: Mass Spectrometer (student textbook p. 281) puts complex scientific techniques in the grasp of Grade 11 students (Expectation D1.1). Developing Skills of Investigation and Communication Chapter 5 The Mole: A Chemist s Counter Students are introduced to the terminology of quantitative relationships (Expectation D2.1) and the relationships between mass, molar mass, and number of particles (Expectations D2.3 and D2.5). In Activity 5.1 One Big Pile of Pennies, students practice unit conversions and using scientific notation. Students then apply their understanding of quantities in chemical reactions in a laboratory setting, analyze data, and communicate findings (Inquiry Investigations 5-A and 5-B). In these investigations, students determine the number of particles present in a sample for a variety of compounds (Expectation D2.3). 3-4 MHR TR Unit 3 Quantities in Chemical Reactions

5 Chapter 6 Proportions in Chemical Compounds Students learn how to determine mass percent and percentage composition from mass data and a chemical formula in Section 6.1 (Expectation 2.2). In Activity 6.1 Mass Percent of Oxygen, they use the data provided to calculate the percent composition of potassium chlorate. Students learn how to determine empirical and molecular formulas in Section 6.2 and Activity 6.2 Exploring Formulas Using Models (Expectation 2.4). They then apply and develop this ability in a laboratory setting (Inquiry Investigations 6-A, 6-B, and 6-C). The career of geotechnical engineer and the contributions of Canadian scientist Scott Dallimore are presented in Quirks & Quarks: Bubbling Methane in the Beaufort Sea (student textbook p. 280), which examines alternate sources of energy and their environmental implications. Chapter 7 Chemical Reactions and Stoichiometry Throughout Chapter 7, beginning with Chapter 7 Launch: Comparing Mole Relationships, students solve problems related to quantities in chemical reactions (Expectations D2.5 and D2.6). In Section 7.2 Limiting and Excess Reactants, students use numerical values to describe what is occurring in chemical reactions. Activity 7.2 Identify the Limiting Item sharpens the inquiry skills needed in Inquiry Investigation 7-A Limiting and Excess Reactants (Expectation D2.6). Section 7.3 Reaction Yields provides the theory required to begin the lab work that addresses Expectation 2.7. Activity 7.4 Increasing Percentage Yield delves into the concepts that support the calculations. Students then conduct inquiries to determine the actual, theoretical, and percentage yield of the products of a chemical reaction, assess the effectiveness of the procedure, and suggest sources of experimental error (Inquiry Investigations 7-B and 7-C). Investigation 7-C also provides some experience with solutions, preparing students for the next unit. Understanding Basic Concepts Chapter 5 The Mole: A Chemist s Counter Section 5.1 The Mole and the Avogadro Constant lays the conceptual and mathematical foundation for working with chemical quantities. Students explore the mole concept and relate it to the Avogadro constant (Expectation D3.2). They then learn to work with the relationships between amounts in moles, the Avogadro constant, and the molar mass of a substance (Section 5.2). Chapter 6 Proportions in Chemical Compounds Students understanding of the law of definite proportions (Expectation D3.1) is developed throughout Section 6.1, including in Activity 6.1 Mass Percent of Oxygen and Inquiry Investigation 6-A Determine the Percentage Composition of Magnesium Oxide. The relationship between the empirical and molecular formula of a chemical compound (Expectation 3.3) is then developed (Section 6.2, Activity 6.2, and Inquiry Investigation 6-B). Chapter 7 Chemical Reactions and Stoichiometry Section 7.1 What Is Stoichiometry? teaches the basics of stoichiometry while building on concepts developed in previous chapters. Students work with simple reactions to build an understanding of the quantitative relationships expressed in a balanced chemical equation (Expectation 3.4) and the fundamentals of limiting and excess reactions. Activity 7.1 Chalk It Up to Molar Relationships uses these skills in a simple laboratory activity, allowing students to further conceptualize word problems as they are presented. Unit 3 Quantities in Chemical Reactions MHR TR 3-5

6 Differentiated Instruction Differentiated Instruction is most effective when students are encouraged to become more aware of their level of prior knowledge, their science skills, how they learn best, how they process learning, and what their interests are. They can then better communicate their needs for support. Assessing Student Readiness Use the questions in the Unit 3 Preparation on pages of the student textbook to establish any current knowledge gaps and assign activities to help bridge the gaps before beginning the unit. Students can fill in the answers to the Unit 3 Preparation questions in their notebooks or use the on-line version at McGraw-Hill Ryerson s CONNECT. (The on-line version provides links to support material.) To understand and work with chemical quantities, students must be comfortable with unit conversions, proportional reasoning, and solving for unknown values. Students who rely on formula alone have difficulty with advanced questions, as they lack an understanding of what the numbers represent. Student readiness can be assessed through read-world scenarios where students work through simple questions while demonstrating the prerequisite math skills. Several examples of this are provided in the Chapter 5 teaching notes. Students frequently demonstrate problems stemming from a weak grasp of nomenclature and inexperience in balancing chemical equations. Ongoing practice with nomenclature is recommended through formative quizzing (with corrections), ticket-out-the-door cards, or through stations and rotation. As students frequently have trouble transferring material between units and courses, an explanation of the course direction will be useful. You can describe the course as a tree. In Unit 3, two roots (pre-existing math knowledge and basic chemistry from Units 1 and 2) meet. The remainder of the course is the trunk, where both lines of information are used concurrently. The Grade 12 course forms branches that build on this Grade 11 foundation. 3-6 MHR TR Unit 3 Quantities in Chemical Reactions

7 Unit 3 Preparation Topics Ionic and Molecular Compounds Student Knowledge Gaps Writing a chemical formula from a chemical name Difference between a molecule and ionic compound Intervention Have students review student textbook pages and Check to see whether students understand the contents of Tables 2.3 and 2.6 for ionic compounds, and of Tables 2.10 and 2.11 for molecular compounds. Also refer students to Appendix B in the student textbook: Names and Formulas of Ions and Names (p. 622), Formulas for Compounds (p. 624), and Rules for Naming Binary Molecular Compounds (p. 625). Refer students to Section 2.3 and to Appendix B: Bond Character (p. 626). Chemical Reactions Evidence of a chemical reaction Have students review Identifying Evidence of a Chemical Change (p. 108). Balanced Chemical Equations Predicting Chemical Equations Types of chemical reactions The same number of each kind of atom must appear in the reactants and products. Writing a chemical equation from a word problem Refer students to Table 3.6: Characteristics of Synthesis, Decomposition, and Combustion Reactions (p. 143). Have students review the Chapter 4 Summary: 4.1 and 4.2 (p. 200) Have students review Writing Balanced Chemical Equations (p. 117) and Table 3.3: Steps for Balancing Chemical Equations (p. 118). Have students work through the sample problem Balancing Chemical Equations (p. 120). Refer students to Appendix B: Some Common Polyatomic Ions (p. 623) Math Skills The metric system Refer students to Appendix A: Measurement (p. 611). Unit conversions See approaches discussed in Ideas for Launching the Chapter in the teaching notes for Chapter 5. Provide BLM 5-1 Working with Units. Uncertainty of measurements Refer students to Appendix A: Measurement (p. 611). Provide BLM G-17 Precision and Accuracy. Scientific notation Refer students to Appendix A: Scientific Notation (p. 616). Provide BLM G-19 The Metric System and Scientific Notation. Significant digits and rounding Solving for a variable in a mathematical equation Ratios, proportions, and/or percents Problem solving Refer students to Appendix A: Significant Digits and Rounding (p. 616) Provide BLM G-18 Significant Digits and Rounding. All examples in the student textbook illustrate the correct use of significant figures. Reinforce this concept daily. Review the concept of solving for x and the use of equations. Stress that both sides of the equation must always be treated in the same way. Have students write out each and every step when solving equations. Most students will be able to get the hang of ratios and percents with a little extra help. Start with simple realworld examples, such as 2 cats: 3 dogs; 5 pets. Emphasize the importance of organization. Have students write out all of the givens and what is required. Provide BLM G-27 Problem Solving Using GRASP. Unit 3 Quantities in Chemical Reactions MHR TR 3-7

8 Assessment Overall Expectations Assessment FOR Learning Support Assessment OF Learning Relating Science to Technology, Society, and the Environment D1. analyse processes in the home, the workplace, and the environmental sector that use chemical quantities and calculations, and assess the importance of quantitative accuracy in industrial chemical processes Case Study, p. 248 BLM A-27 Interpreting Data Rubric Unit 3 Project, p. 336 Investigation 6-B, p. 284 Chemistry Connections, p. 281 BLM A-4 Making Observations and Inferences Checklist Unit 1 Project Rubric Activity 7.3, p. 312 Activity 7.4, p. 320 Case Study, p. 328 BLM A-4 Making Observations and Inferences Checklist BLM A-10 Presentation Checklist BLM A-31 Gathering Information Rubric BLM A-32 Presentation Rubric Developing Skills of Investigation and Communication D2. investigate quantitative relationships in chemical reactions, and solve related problems Investigation 5-A, p. 244 Investigation 5-B, p. 246 Activity 6.1, p. 260 Activity 6.2, p. 276 Investigation 6-A, p. 281 Investigation 6-B, p. 284 Investigation 6-C, p. 286 Appendix A Significant Digits and Rounding, student textbook p. 614 Appendix A Scientific Notation p. 616 Appendix A Measurement, student textbook p. 612 BLM A-20 Predicting Rubric BLM A-25 Conducting an Investigation Rubric Unit 3 Project, p. 336 Unit 1 Project Rubric Activity 7.2, p. 307 Activity 7.4, p. 320 Investigation 7-A, p. 322 Investigation 7-B, p. 324 Investigation 7-C, p. 326 Practice Problems, p. 298, p. 300, p. 304, p. 309, p. 311, p. 319 BLM 7-2 Scaffolding for Activity 7.2 BLM A-4 Making Observations and Inferences Checklist BLM A-7 Data Table Checklist Understanding Basic Concepts D3. demonstrate an understanding of the mole concept and its significance to the quantitative analysis of chemical reactions Reviews, p. 305, p. 313, p. 321 Chapter 7 Review, p. 332 Unit 3 Review, p. 339 Activity 5.1, p. 227 Investigation 5-A, p. 244 Investigation 5-B, p. 246 Learning Checks, p. 226, p. 234 Practice Problems, p. 228, p. 230, p. 231, p. 235, p. 237, p. 239, p & 5.2 Reviews, p. 232, p. 243 Chapter 5 Review, p. 251 BLM 5-2 GRASPing Molar Quantities BLM 5-4 Counting to a Mole BLM 5-5 Activity 5.1 Scaffolding BLM 5-8 Working with the Mole I IV BLM 5-9 Mole Review Activity Unit 3 Project, p. 336 Unit 1 Project Rubric 3-8 MHR TR Unit 3 Quantities in Chemical Reactions

9 Overall Expectations Assessment FOR Learning Support Assessment OF Learning Activity 6.1, p. 260 Activity 6.2, p. 276 Investigation 6-A, p. 282 Investigation 6-B, p. 284 Learning Checks, p. 262, p. 270, p. 277 Practice Problems, p. 260, p. 264, p. 266, p. 273, p. 275, p & 5.2 Reviews, p. 267, p. 279 Chapter 6 Review, p. 290 Activity 7.1, p. 301 Learning Checks, p. 299, p. 309, p. 316 Summative Assessment: Unit 3 Project Modelling Copper Recovery in the Electronics Industry (Student textbook pages ) Students will apply their understanding of quantitative relationships in chemical reactions to design a cost-effective and efficient procedure to recover copper metal from etching waste (copper(ii) nitrate solution) (Overall Expectation D1). They will apply the investigation skills and conceptual knowledge developed over the course of the unit as they write equations for possible reactions; research and design procedures; consider safety issues; conduct inquiries to collect qualitative and quantitative data; perform calculations to determine the yield for each reaction; and analyze their results and draw conclusions (Overall Expectations D2 and D3). They will demonstrate a wide range of communication skills through the creation of data and observations tables, flowcharts, and written procedures; drawings or photographs of reactions and graphs of yields; and a final report and presentation. There are many opportunities here to display insight and imagination. Preparing for the Unit Project For students with a good handle on the material, the project will follow smoothly from the previous lessons. The majority of the class will benefit from ongoing discussions regarding the unit project and specific references to key steps: Introduce the project at the beginning of the unit, when students have recently encountered types of reactions and the activity series. Provide BLM 7-7 Unit 3 Project Planning Guide. At this point, students should be able to identify the metals they will investigate and the overall reaction equations. Encourage students to complete step 2 before beginning Chapter 7, and to give some thought to questions 3 and 4. This will create questions and anticipation for the lessons in chapter 7 and a deeper conceptual understanding. At the end of each lesson during chapter 7, refer to the project and ask students to apply daily learning to build their procedure. Remind students that you must approve their procedure and safety precautions before they conduct their investigation. Unit 3 Quantities in Chemical Reactions MHR TR 3-9

10 scienceontario Links for Unit 3 As of the printing of this Teacher s Resource, the following links were established for the Chemistry 11 student edition. Chapter 5: The Mole: A Chemist s Counter Page 225 Using the Mole to Count Particles A McGraw Hill applet on the mole concept; includes a quiz. Page 228 From Dozens to Moles A McGraw Hill applet on the mole method for molar mass. An introduction to Section 5.2, Mass and the Mole Chapter 6: Proportions in Chemical Compounds Page 263 An Application of Percentage Composition Walter Norman Haworth: An account of the Nobel-prize-winning scientist s work in synthesizing vitamin C (text only). Page 271 Determining the Empirical Formula McGraw applet on chemical analysis; slides 3 and 4 address molecular and empirical formulas Page 280 Quirks and Quarks: Bubbling Methane in the Beaufort Sea Quirks and Quarks Podcast January 27, 2007exploring pingoes mounds on the seafloor that could be tapped as a resource for natural gas Chapter 7: Chemical Reactions and Stoichiometry Page 296 Figure 7.2 and its associated paragraph Link to Environment Canada s resources on Pollution and Waste One-stop shopping for information on pollutants, their sources, management, and prevention in Canada Page 302 Stoichiometric Mass Calculations A brief applet on theoretical yields vs. actual yields MHR TR Unit 3 Quantities in Chemical Reactions

11 Notes Unit 3 Quantities in Chemical Reactions MHR TR 3-11